Casing hook



July 26, 1938- G. F. FERMIER ET AL CASING HOOK Filed June 20, 1956 3Sheets-Sheet l gmc/wim. ermz'e/T 5t a/r es July 26, 1938. G. F. FERMIERET AL CAS ING HOOK Filed June 20, 1936 5 Sheets-Sheet 2 U0 m, u.,

Il/IIIIIIIIIIIII lill YIIIIIII A July 26, 1938. G. F. FERMIER ET ALCASING HOOK Filed June 20, 1936 3 Sheets-Sheet 3 4a g 97 -s -95 II.,lag@ atenter `luly' 26, 19358 UNITED STATES PATENT OFFICE CASIN G HOOKApplication June 20, 1936, Serial No. 86,255

18 Claims.

This invention relates to that type of hooks customarily employed in theconstruction and operation of oil and gas wells for supporting thecasing or drill pipe employed during the drilling operation.

This invention has to do particularly with a resilient hook which willeffectively support the weight of a portion of a drill pipe beingunscrewed and which will lift such portion away from the part from whichit is disconnected as soon as the threads are disengaged.

Hooks of this type are commonly used in putting in or pulling wellcasings o1' drill stems, to support a section of the casing while it isbeing unscrewed from the other sections. The separation of the sectionsis effected by rotating the casing or drill stem at a point below thejoint to be broken by means of a rotary table while the section abovethe joint is held stationary by suitable tongs, or by holding stationarythe casing or drill stem at a point below the joint to be broken whilethe section above the joint is rotated by means of tongs.

In either procedure some means is provided to take up the weight of theupper section during the breaking of the joint, because unless this isdone, the weight of the section rests on the screw threads of the jointand tends to grind off and damage the threads. To obviate this damage tothe screw threads, and for the purpose of saving time, it is common tosupport the section being removed by a casing hook provided with acompression spring of such strength as to support the section during thebreaking out of the taperthreaded joint, and later after disengagementof the threads to automatically lift said section high enough to free itfrom all interference with its former mating member.

Where such hooks are provided With merely a spring for lifting the pipesection once it has been disconnected, it has frequently beenexperienced that an operator is unable to push the section removed asideexactly the moment it is pulled upwardly by the spring, and that on therecoil the section removed will come back 'down and frequently hitagainst the joint from which it has just been disconnected. This isobviously detrimental tothe threads of the joint and causes considerabledamage and delay when it occurs. Furthermore, it is not an unknownoccurrence for a workmans hand to slip between the sections when thesection is rst lifted, and to be greatly injured when the sections cometogether again on the recoil.

It is the purpose of this invention to provide a casing hook in whichthe recoil referred to will be eliminated.

It is a further object of this invention to provide a casing hook whichwill serve to quickly remove the section from the joint from which it isdisconnected, but which will retard any tendency toward recoil andprevent the two parts of the joint from being hammered together oncethey have been separated by the spring of the casing hook.

With the foregoing and other objects in view, this inventioncontemplates the various parts and combinations, and the variousmodifications thereof illustrated in the accompanying drawings.

It is to be understood, however, that while several modications havebeen illustrated, the same are by way of example only, and it is not tobe implied that all possible forms have been shown. It is apparent thatvarious other modifications may be made within the spirit and scope ofthis invention, such spirit and scope being limited only by the priorart and by the terms of the appended claims.

Referring now more particularly to the drawings in which like numeralsindicate corresponding parts throughout;

Fig. 1 is a view partly in vertical cross section illustrating oneembodiment of this invention.

Fig. 2 is a horizontal section taken along the line 2 2 of Fig. 1, andillustrating the adjusting 30 means employed in connection with the formshown in Fig. 1.

Figs. 3 to 8, inclusive, are views similar to Fig. 1, but illustratingvarious modied arrangements of the respective parts.

Figs. 1a, 4a and 8a are enlarged fractional portions of Figs. 1, 4 and8, respectively.

Fig. 9 is a View illustrating the application of a casing hookconstructed in accordance with this invention. 5

Referring rst to the form shown in Fig. 1, the hook l is supported bymeans of a yoke 2 or the like, such yoke having eyelets 3 at its lowerends adapted to be received on the pintles 4 of the block 5. The eyelets3 are held on the pintles 4 45 by means of cap screws 6 or the likewhich secure the washers 1 in place.

The block 5 is provided with a central bore having a reduced portion atits upper end within the externally threaded extension 8 of the block 5.50 Threaded onto this extension 8 is a tubular member or cylinder 9which extends upwardly from the block. A passageway l0 constituting abypass is formed through the extension 8 in a longitudinal direction andcommunicates with the inte- 55 CII rior of the tubing 9 and with theinterior of the lower portion of the bore through the block 5. The'sizeof this passageway I0 may be regulated by suitable means such as a screwvalve II. A second passageway I0', spaced from the passageway I0, alsoextends between the interior of the tubing 9 and with the interior ofthe lower portion of the bore through the block 5. This passageway IIIis controlled by a ball valve I I which permits free movementtherethrough in an upward direction but prevents movement therethroughin a downward direction.

The hook has a portion fitting within the lower part of the boreA in theblock 5 and provided with a cup-shaped Washer I2 so as to form a fluidseal between this portion of the hook and the walls of the bore in theblock. Thewalls I3 of this bore are machined smooth so that the packingor washer I2 may slide therein with the least possible friction and forma good seal. Above the washer I2 the hook I carries a stem I4 of reducedsize, and the upper end of this stem is threaded at I5 to receive a nutI6 forming a plunger which rides up-and down within the cylinder 9. At apoint adjacent its lower end this plunger is provided with a cup-shapedwasher I1 similar to the washer I2 on the lower portion of the hook withthe exception that the washer I1 is inverted. The upper end of the nutI6 is provided with a head which extends laterally and limits thedownward movement not only of the nut I6, but of the hook I as well.This nut I6 is locked in place by means of a lock nut I9.

Positioned below the lower end of the nut I6 and seated on the upper endof the extension 8 of the block 5 is a compression spring 20 which isadapted to support the weight as hereinbefore referred to. A plug orother means may be provided adjacent the upper end of the cylinder 9 forthe purpose of atl least partially filling this cylinder and the lowerportion'of the bore through the block 5 with a suitable liquid, whichliquid will act with a dashpot effect when the hook is operated as willnow be described.

The hook I is connected to a section of pipe and an upward pull exerteduntil the spring 20 is compressed to the extent that the force exertedby the spring will be suicient to raise the section of pipe as soon asit is disconnected. When the section is disconnected, the force of thespring will cause the pipe to be raised quickly, the fluid passingfreely upwardly through passageway I0', until the joint at the lower endof the pipe is free from the joint to which it has just beendisconnected. The dashpot eiect of the fluid now comes into play, thevalve Il closing and the fluid on its downward movement being forcedpast the metering screw II. This prevents any rapid downward movement ofthe hook, and consequently of the pipe section which has just beenremoved. This dashpot arrangement thereby takes up the recoil whichwould ordinarily be taken up by the spring itself, and prevents thedownward recoil movement which has been referred to above.

In the form illustrated in Fig. 3, the hook 2l is supported by the yoke22, the lower ends of which are formed with eyelets 23 engaging the lugs24 in a manner very similar to that illustrated in Fig. 1. The lugs 24are carried on a block 25 which is for the most part hollow and open atits upper end, but which is provided with an upstanding cylindricalportion 26 centrally thereof. The cylindrical portion 26 when taken withthe outer walls of the block 25 provide an inner cylindrical chamber 21and an outer annular chamber 28. Passing through the inner chamber isthe stem 29 which is integral with the upper end of the hook 2|, andsurrounding this stem 29 is the compression spring 30 corresponding tothe spring 29 of Fig. 1. The stem 29 is threaded at its upper e'nd as at3| to receive an inverted cup-shaped plunger member 32. This member 32has downwardly extending walls 33 carryingv at their lower ends anannular plunger 34 which is of such a size as to fit fairly snuglywithin the annular chamber 28. This plunger 34 is .provided with aby-pass 35 extending from its upper to its lower surface. In addition tothe bypass 35 through the plunger 34, the block 25 is also provided withtwo or more by-passes. One of these by-passes 36 is normally closed toprevent movement of the fluid therethrough from the space below theplunger to the space above the same by means of a check valve 31. Thecheck valve 31, however, is arranged to permit free movement of thefluid from the space above the plunger to the space below the same. Theother by-pass 38 is likewise provided with a check valve 39, this checkvalve being spring pressed by a spring 40 to retard movement of fluidfrom below the plunger to the space above the same, and to positivelyprevent movement of fluid from the space above the plunger to the spacebelow the same. ,Y

The upper end of the block 25 is preferably closed by a plate or dome 4Isecured in place by means of cap screws or the like 42.

In this form, the operation is similar to that illustrated in Fig. 1with the exception that upon upward movement of the hook 2I the fluid ispermitted to pass freely through the by-pass 36 in the block 25 and thuspermit the upward movement of the hook to be swift and sudden. On theother hand, the downward movement is limited both by the size of theopening 35 and by the strength of the spring 40 so that the recoil whichit is desired to eliminate will be effectively damped.

With reference to the form illustrated in Fig. 4, this is very similarto that shown in Fig. 3. In this form the hook 43 is supported by theyoke 44 having the eyelets 45 in engagement with the lugs 46- on theblock 41. An upstanding cylindrical wall 48 is provided within thisblock 41, the same being very similar to the wall 26 in Fig. 3. Passingthrough the chamber 49 within this cylindrical wall 48 is the stem 5I onthe hook 43 and the spring 52 surrounds this stem in precisely the samemanner as shown in Fig. 3. Secured to the threaded upper end 53 of thestem 5I is the plunger member 54 which has downwardly extending walls 55carrying the annular plunger 56. In this instance, the annular plungeris so formed as to fit the annular chamber 50 loosely. 'I'he plunger isprovided with a bypass opening 51 therethrough similar to the opening 35of Fig. 3. On the lower surface of this annular plunger there is mounteda U-shaped packing Washer 58 secured in place by means of a ring 59 heldto the plunger by cap screws 60 or the like. The upper end of the block41 is closed by a plate or dome 6I held to the block by screws 62 in themanner readily apparent.

The operation of this hook is likewise similar to that shown in Fig. 3,the exception being that upon upward movement of the hook the uid isallowed to pass from above the piston to the space below the piston byvirtue of the shape of the cup-shaped packing 58, the by-passes 36 and36 in the block being omitted.

In the form shown in Fig. a somewhat diierent arrangement is provided.'I'he hook 63 in this instance is supported by a yoke 64 having eyelets65 mounted on the lugs 66 of the block 61`.

. The block 61, however, is provided with two cy- QJI lindrical chamberstherein 68 and 69, these chambers being connected at their lower ends bya passageway 10. 'I'here is also a passageway 1| which connects theupper en'ds of these cylindrical chambers, and which passes adjacent thelower end of the cylindrical chambers and adjacent the passageway 10.'I'he passageways 10 and 1| are interconnected by means of arestrictedopening 12, and also by means of an opening 13 controlled by a ballValve 14 normally urged into seated position by a spring 15. The lowerends of the chambers 60 and 69 are also connected to the passageway 1|,these connections being controlled by the ball valves 16 and 11,respectively, so positioned as to permit passage of fluid from thepassageway 1| into the respective chambers, but to prevent such passagein the opposite direction. The balls 16 and 11 are retained adjacent theopenings they control by means of guards 10 and 19.

The upper ends of the chambers 00 and 99 are closed by means of plugs 80and 8|, respectively, threaded into the upper ends of the chambers. Eachof these plugs is provided with an opening through which the piston rods32 and 83 are adapted to move. These piston rods carry the pistons 84and 85, respectively, and are connected at their upper ends by means ofa cross head 90. The cross head 86 is secured to the upper end of thestem of the hook by means of a nut 0l' or the like, the connection beingloose so that the hook may swivel with respect to the plungers. The hookin this instance extends upwardly through the block, and is providedwith a compression spring surrounding its stem in substantially the samemanner as illustrated in Fig. 7 of the drawings.

In operation, the device of Fig. 5 permits rapid movement of the hookupwardly, the fluid within the cylindrical chambers 60 and 69 passing insuch instance from the space above the pistons through the passageway 1|and into the space below the pistons through the valves 16 and 11. 0ndownward movement, however, the hook is forced to move slowly by thedashpot eifect created by the necessity for the fluid in moving frombelow the pistons to above the same to pass through the restrictedopening 12, and through the passageway 13 controlled by the springpressed valve 14.

in Fig. 6, the hook 88 is supported by a yoke 89 having eyelets 90engaging the plugs 9| on the block 92 in substantially the same manneras hereinbefore described. The block 92, however, is in this instanceformed with a single cylindrical chamber 93 and with a passageway 94connecting the upper end of this chamber with the lower end thereof.Adjacent the lower end of the chamber this passageway 94 communicateswith the interior of the chamber through a restricted openingV 95, andat its lower end this passageway is controlled by a valve 96 retained inplace by a guard 91. As will be seen,l this valve is such as to permitfree passage of fluid into the lower end of the chamber, but to preventpassage from the lower end of the chamber except through the restrictedopening 95.

The upper end of the cylindrical chamber 93 is closed by a threaded plug98 having an opening therethrough receiving the slidable piston rod 99.On its lower end this piston rod carries the piston |00 which isreciprocable in the cylindrical chamber and secured at its upper end isthe cross head |0|. 'I'his cross head |0| is secured to the stem of thehook 88 by a nut |02 or the like, these connections and the spring whichsurrounds the stem of the hook within the block 92 being substantiallythe same as that illustrated in Fig. '1 now to be described.

It will be appreciated that in this form the hook 88 is permitted tomove upwardly without restriction, the uid which is employed within thecylinder 93 passing in such instance from the upper portion of thecylinder to the lower portion of the cylinder through the valve 96. Onits downward movement, however, it is restricted to passage through thesmall opening 95 and the recoil is thus substantially eliminated.

In Fig. '7, the arrangement is substantially the same as in Fig. 6, thehook |03 being supported by a yoke |00 which is in turn secured to theblock |05 in substantially the same manner. The block |05 is similarprovided with a single cylindrical chamber |00 and with a passageway |01connecting the upper portion thereof with the lower portion thereof.rl'he lower end of this passageway communicates with the interior of thechamber |06 through two openings, one of which is controlled by a springpressed valve |00 held in place by a spring |09, and the other oi whichis controlled by a call valve ||0 retained by a guard iii. The upper endof the chamber is closed by a plug ||2 formed to accommodate the pistonrod ili carrying a piston lill at its lower end. At its upper end across head H5 is provided. By means of a castle nut H0, the cross headiliiis secured to a fitting M0 in such a manner as to permit the fittingto swivel with respect to the cross head. This itting is in turnthreaded at liti to the upper end of the stem |20 on the hook |03.Surrounding the stem |20 between the lower portion of the block |05 andthe fitting H0 is a compression spring |2i, this spring having the samefunction as the springs illustrated in Figs. i, 3 and In this form ofhook, upward movement of the hook is permitted freely by virtue of thefact that the fluid which is used within the cylindrical chamber |06 maypass from above the piston through the passageway |01 and upwardly intothe space below the piston through the valve I0. On downward movement,however, the fluid must pass by the spring pressed valve |00, thestrength of the spring |09 being such as to damp the movement of thepiston by restricting the movement of the fluid from below the piston.

In the illustration of Fig. S, the hook |22 is supported by the yoke |23having eyelets |24 on its lower ends engaging the plugs |25 on the block|26. The block |26 has a cylindrical chamber therein at |21, but is notprovided with any passageways corresponding to those described in thepreceding paragraphs. The upper end of the chamber |21 is closed by aplug |28 which is formed to provide for the passage of the piston rod|29. The piston |30 is carried on the lower end of this rod and fitsloosely within the chamber |21. A cup-shaped packing |3| is secured tothe lower face of the piston' |30 by means of a plate |32 and cap screwsor the like |33. Extending through the piston |30, the packing |3|, andthe plate |32, is a passageway |34 of such i pipe.

size as to restrict the passage of fluid therethrough.

The upper end of the piston rod |29 is secured to a cross head |35 whichis in turn secured to the upper end of the stem or hook |22 by means ofa nut |36 or the like. The connection between the hook |22 and the nut|36 is similar in all respects to the corresponding structure shown inFig. 7.

In this form, the upward movement of the hook |22 is unrestrictedbecause of the fact that the fluid which is used in the chamber |21 maypass unrestrictedly by the piston |30 and the cup-shaped packing |3|. Ondownward movement, however, the fluid is held by the packing |3| and iscompelled to pass through the restricted passageway |34 in moving frombelow the piston to the space above the same. Any recoil is therebytaken up.

The application of the various casing hooks above described isillustrated in Fig. 9, the hook of Fig. 3 being shown here for purposesof illustration. It will be seen that the hook 2| in this instance isengaged with a yoke |31 secured to a clamp |38 by which the section oftubing |39 is being held. On the lower end of this section of tubing isthe pin portion of a tool joint |40, the box portion |4| being on theupper end of the string of pipe |42. This string is in this instancesupported by means of slips |43 carried by a suitably supported block|44 in a manner which is well known to those skilled in the art. When itis desired to disconnect a section such as |39, the section is pulled toa point above the support |44 and the slips |43 are then engaged tosupport the lower portion of the string of A sufficient force is exertedon the hook 2l to compress the spring 30 included therein, and to movethe annular piston 34 to its lowermost position. The tool joint sections|40 and |4| are thereupon unscrewed to disjoint the section |39.Immediately upon disengagement of the threads of the respective parts ofthe tool joint the spring 30 will expand andcause the annular piston 34to be raised to its uppermost position within the annular chamber 28. Insuch .movement fluid is permitted to pass from above the piston throughthe passageway 36 and pass the Valve 31, no restriction being imposedupon this passage of fluid. This leaves the section |39 in the positionillustrated in Fig. 9. Naturally, there is a. tendency for a recoil totake place, and for this section to again move downwardly tending tobring the threaded ends of the tool joint into engagement the secondtime. This is prevented, however, in this instance by virtue of the factthat the iluid is trapped in the annular space below the piston 34, andbefore this piston can move downwardly, and hence before the hook 2| andthe section |39 can move downwardly, the fluid must either pass throughthe small opening 35 in the piston, or must be forced past the springpressed valve 39, and through the passageway 30. Since it requiresconsiderable time for the fluid to pass from one space to the other byeither of these routes, the tendency to recoil is effectively overcome.

In the foregoing description and in the following claims this inventionhas been referred to as a casing hook. It will be understood, however,that this term is not intended as in any way a limitation, but that itis intended that this invention shall include all hooks of the natureclaimed which are capable of being employed either during the removal ofa casing from a well, or during the removal of a drill stem, or duringthe removal of any other pipe or rod from a well or other opening.

It will also be understood that the term hook is to be taken asincluding elements notnecessarily shaped as hooks but performing thefunction of hooks disclosed in this application and that the term "yoke"is likewise to be taken as including elements shaped differently fromthe yoke elements disclosed in the drawing of this application butperforming substantially the same function, namely, the function of apendant support.

In view of the foregoing, it will be seen that a means has been providedfor carrying out all the objects and advantages sought by thisinvention.

Having described our invention, we claim:

l. In a casing hook, in combination, a yoke member, a spring supportedthereby, a hook member supported on said spring, a dashpot havingrelatively movable parts connected to said yoke and to said hook,respectively, said dashpot including means for retarding withoutsubstantially restricting downward movement of said hook whilepermitting substantially free upward movement thereof with respect tosaid yoke.

2. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber therein, v

a spring carried by said member, a hook supported on said spring, apiston in said chamber and connected with said hook for movement in saidchamber on upward or downward movement of said hook, and means forretarding a flow of fluid past said piston on downward movement of saidhook and for conducting such uid freely past said piston on upwardmovement of said hook, whereby said hook will be retarded on downwardmovement, and free from retardation on upward movement.

3. In a casing hook, a yoke, a member carried by said yoke and having aliquid chamber therein, a spring carried by said member, a hooksupported on said spring, a plunger movable in said chamber andconnected with said hook for movement in said chamber on downwardmovement of said hook, a liquid in said chamber, and means retarding theescape of said liquid from its position in said chamber ahead of saidplunger on downward movement of said hook.

4. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, a spring in said springchamber, a hook supported on said spring, a plunger in said fluidchamber and connected with said hook for movement in said chamber ondownward movement of said hook, a fluid in said chamber, and meansretarding the escape of said fluid from its position in said chamberahead of said plunger upon downward movement of said hook.

5. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, a spring in said springchamber, a hook supported on said spring, a plunger in said fluidchamber and connected with said hook for movement in said chamber ondownward movement of said hook, a swivel connection between said hookand said plunger, a fluid in said chamber, and means retarding theescape of said fluid from its position in said chamber ahead of saidplunger upon downward movement of said hook.

6. In a casing hook, a yoke, a. member carried by si id yoke and havinga fluid liamber and a spring chamber therein, said fluid and springchambers being spaced laterally from each other, a spring in said springchamber, a hook supported on said spring, a plunger in said fluidchamber and connected with said hook for movement in said chamber ondownward movement of said hook, a fluid in said chamber, and meansretarding the escape of said fluid from its position in said chamberahead of said plunger upon downward motion of said hook.

7. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, said fluid and springchambers being substantially concentric with respect to each other, aspring in said spring chamber, a hook supported on said spring, aplunger in said fluid chamber and connected with said hook for movementin said chamber on downward movement of said hook, a fluid in saidchamber, and means retarding the escape of said fluid from its positionin said chamber ahead of said plunger upon downward motion of said hook.

8. In a casing hook, a yoke, a member carried by said yoke, and having afluid chamber and a spring chamber therein, a spring in said springchamber, a hook supported on said spring, a piston in said fluid chamberand connected with said hook for movement in said chamber on downwardmovement of said hook, a fluid in said chamber, means retarding theescape of said fluid from its position ln Ysaid chamber ahead of saidplunger upon downward motion o f said hook, and for freely conductinguid into said chamber upon upward motion of said hook.

9. In a casing hook, a yoke, a member carried by said yoke and having afluid chamberand a spring chamber therein, said fluid and springchambers being substantially concentric and said fluid chamber being ofannular form, a spring in said spring chamber, a hook supported on saidspring, an annular plunger in said annular fluid chamber and connectedwith said hook for movement in said chamber on downward movement of saidhook, a fluid in said chamber, and means retarding the escape of saidfluid from its position in said chamber ahead of said piston upondownward motion of said hook.

10. In a casing hook, a yoke, a member carried by said yoke and having aliquid chamber therein, a spring carried by said member, a hooksupported on said spring, a plunger movable in said chamber andconnected with said hook for movement in said chamber on downwardmovement of said hook, a liquid in said chamber, and means retarding theescape of said liquid from its position in said/chamber ahead of saidplunger upon downward motion of said hook and for freely admitting fluidto said chamber upon upward motion of -said hook.

11. In a casing hook, a yoke, a member carried by said yoke and havingaliquid chamber therein, a spring within said liquid chamber, a hooksupported on said spring, a plunger movable in said chamber andconnected with said hook for movement in said chamber on downwardmovement of said hook, a liquid in said chamber, and means retarding theescape of said liquid from its position ln said chamber ahead of saidplunger upon downward motion of said hook.

12. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, said fluid and springchambers being spaced laterally from each other,

a spring in said spring chamber, a hook supported on said spring, aplunger in said fluid chamber and connected to said hook for movement insaid chamber on downward movement of said hook, a fluid in said chamber,said chamber having a restricted opening therein for permltting retardedescape of said fluid from its position in said chamber ahead of saidplunger upon downward movement of said hook, and a freely operatingcheck valve for freely admitting fluid to said chamber upon upwardmovement of said hook.

13. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, said fluid and springchambers being spaced laterally from each other, a spring in said springchamber, a hook supported on said spring, a plunger in said fluidchamber and connected with said hook for movement in said chamber ondownward movement of said hook, a fluid in said chamber, said chamberhaving a restricted opening therein for permitting unrestricted escapeof said fluid from its position in said chamber ahead of said plungerupon downward movement of said hook, a springpressed check valvearranged to permit additional escape of said fluid upon placing of anexcessive load on said hook, and a freely operating check valve forfreely admitting fluid into said chamber upon upward movement of saidhook.

14. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, said fluid and springchambersbeing spaced laterally from each other, a spring in said springchamber, a hook supported on said spring, a plunger in said fluidchamber and connected with ksaid hook for movement in said chamber ondownward movement of said hook, a fluid in said chamber, a flexiblecupshaped washer on said plunger for preventing movement of said fluidbetween the walls of said chamber and the sides of said plunger upondownward movement of said hook, but permitting relatively free movementof said fluid in the opposite direction upon upward movement of saidhook, and said plunger having a restricted passageway therethrough forpermitting retarded escape of said fluid from its position in saidchamber ahead of said plunger upon downward motion of said hook.

15. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, said fluid and springchambers being substantially concentric with respect to each other, aspring in said spring chamber, a hook supported on said spring, aplunger in said fluid chamber and connected with said hook for movementin said chamber on downward movement of said hook, a fluid in saidchamber, said chamber having a restricted opening therein for permittingretarded escape of said fluid from its position in said chamber ahead ofsaid plunger upon downward movement of said hook, a springpressed checkvalve arranged to permit additional retarded escape of said fluid uponthe placing of an excessive load on said hook, and a freely movablecheck valve arranged to freely admit fluid to said chamber upon upwardmovement of said hook.

16. In a casing hook, a yoke, a member carried by said yoke and having afluid chamber and a spring chamber therein, said fluid and springchambers being substantially concentric with respect to each other, aspring in said spring chamber, a hook supported on said spring, aplunger in said fluid chamber and connected with said hook for movementin said chamber on downward movement-of said hook, said structure hav.

ing a restricted opening therein for permitting retarded escape of saidiluid from its position in said chamber ahead of said plunger upondownward movement of said hook, and a U-shaped washer on said plungeradapted to slidingly contact the walls of said chamber and preventmovement of said fluid past said plunger upon downward movement of saidhook while permitting substantially free movement of said uid past saidplunger upon upward movement of said hook.

17. In a casing hook, a yoke, a member carried by said yoke and having aspring chamber and a plurality of fluid chambers therein, said fluidchambers occupying balanced positions on oppo-V site sides of saidspring chamber, a spring in said spring chamber, a hook supported onsaid spring, plungers in said fluid chambers respectively, and eachconnected with said hook for movement in said chambers on downwardmovement of said hook, a fluid in said chambers, and means retarding theescape of said fluid from its position in said chambers ahead of saidplungers upon downward movement of said hook.

18. In a, casing hook, a yoke, a member carried site sides of saidspring chamber, a spring in said spring chamber, a hook supported onsaid spring, plungers in said fluid chambers, respectively, and eachconnected with said hook for movement in said chambers on downwardmovement of said hook, a fluid in said chambers, a restricted opening insaid chamber for permitting retarded escape of said fluid from itsposition in said chamber ahead of said plunger upon downward movement ofsaid hook, a spring-pressed check valve arranged to permit additionalretarded escape of said fluid from said chamber upon the placing of anexcessive load on said hook, and a freely movable check valve arrangedto freely admit iluid into said chamber upon upward movement of saidhook.

GEORGE F. FERMIER.

JOHN C. STOKES.

